Advances in manufacturing techniques have allowed transistors to be made with ever smaller geometries. For example, photolithographic and etch techniques have improved to the point where transistors with a gate length of 0.25 microns (μm) may be made. Decreasing the size of transistors is generally perceived to be beneficial because this may allow more transistors to be made within the same amount of area on a semiconductor die.
It may also be generally beneficial to reduce the thickness of the gate dielectric material as the size of the transistor is reduced. Advancements in manufacturing capabilities may allow transistors to be made that have gate dielectric layers measured in monolayers (i.e. layers or atoms). However, as the thickness of the dielectric material is reduced, the leakage current through the material may increase. Thus, the amount of current leakage through the gate of each transistor may increase. This problem may be further acerbated by the trend to increase the number of transistors that make up an integrated circuit.
Thus, there is a continuing need to reduce the leakage current associated with a transistor in an integrated circuit.
It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.